From: "Linux kernel regression tracking (#adding)" <regressions@leemhuis.info>
To: Will Deacon <will@kernel.org>, Waiman Long <longman@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Valentin Schneider <vschneid@redhat.com>,
Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
qperret@google.com
Subject: Re: [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity()
Date: Thu, 26 Jan 2023 13:52:00 +0100 [thread overview]
Message-ID: <cc637c44-3217-21f4-8843-66e99249b38c@leemhuis.info> (raw)
In-Reply-To: <20230117160825.GA17756@willie-the-truck>
[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]
On 17.01.23 17:08, Will Deacon wrote:
>
> On Thu, Sep 22, 2022 at 02:00:38PM -0400, Waiman Long wrote:
>> The user_cpus_ptr field is added by commit b90ca8badbd1 ("sched:
>> Introduce task_struct::user_cpus_ptr to track requested affinity"). It
>> is currently used only by arm64 arch due to possible asymmetric CPU
>> setup. This patch extends its usage to save user provided cpumask
>> when sched_setaffinity() is called for all arches. With this patch
>> applied, user_cpus_ptr, once allocated after a successful call to
>> sched_setaffinity(), will only be freed when the task exits.
> [...]
> We've tracked this down as the cause of an arm64 regression in Android and I've
> reproduced the issue with mainline.
>
> Basically, if an arm64 system is booted with "allow_mismatched_32bit_el0" on
> the command-line, then the arch code will (amongst other things) call
> force_compatible_cpus_allowed_ptr() and relax_compatible_cpus_allowed_ptr()
> when exec()'ing a 32-bit or a 64-bit task respectively.
> [...]
Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:
#regzbot ^introduced 8f9ea86fdf99
#regzbot title sched: incorrectly set affinity masks and performance
regression on arm64
#regzbot monitor:
https://lore.kernel.org/all/20230121021749.55313-1-longman@redhat.com/
#regzbot ignore-activity
This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.
Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.
Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
That page also explains what to do if mails like this annoy you.
next prev parent reply other threads:[~2023-01-26 12:52 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 18:00 [PATCH v10 0/5] sched: Persistent user requested affinity Waiman Long
2022-09-22 18:00 ` [PATCH v10 1/5] sched: Add __releases annotations to affine_move_task() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] sched: Always preserve the user requested cpumask tip-bot2 for Waiman Long
2023-01-17 16:08 ` [PATCH v10 2/5] sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() Will Deacon
2023-01-17 18:13 ` Waiman Long
2023-01-20 17:59 ` Will Deacon
2023-01-20 18:10 ` Waiman Long
2023-01-26 12:52 ` Linux kernel regression tracking (#adding) [this message]
2023-02-10 17:15 ` Linux kernel regression tracking (#update)
2023-01-27 18:36 ` Peter Zijlstra
2023-01-27 19:09 ` Waiman Long
2022-09-22 18:00 ` [PATCH v10 3/5] sched: Enforce user requested affinity Waiman Long
2022-10-07 10:01 ` Peter Zijlstra
2022-10-07 14:57 ` Waiman Long
2022-10-07 15:23 ` Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 4/5] sched: Handle set_cpus_allowed_ptr(), sched_setaffinity() & other races Waiman Long
2022-10-07 12:47 ` Peter Zijlstra
2022-10-07 18:59 ` Waiman Long
2022-10-28 6:42 ` [tip: sched/core] sched: Introduce affinity_context tip-bot2 for Waiman Long
2022-09-22 18:00 ` [PATCH v10 5/5] sched: Always clear user_cpus_ptr in do_set_cpus_allowed() Waiman Long
2022-10-28 6:42 ` [tip: sched/core] " tip-bot2 for Waiman Long
2022-10-06 21:31 ` [PATCH v10 0/5] sched: Persistent user requested affinity Waiman Long
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